1. Field of the Invention
This invention relates to carpenters' claw hammers for driving and removing nails and striking various objects, and in particular, shock absorbing or dead blow hammers that reduce the recoil and vibration caused by the hammer strike. More particularly, the present invention relates to a shock absorbing hammer including a claw feature and a natural hickory wood, fiberglass, steel or other material handle.
When a percussive tool such as a hammer strikes the surface of an object, part of the energy produced by the strike is used to perform desired work, (e.g. drive a nail) part is converted into heat, and part is dissipated through the hammer. The energy dissipated through the handle often produces undesirable results such as recoil of the hammer from the object being struck or excessive vibration. These undesirable effects have been a persistent problem for the makers of hammers and other percussive tools. Many users of hammers prefer the vibration-reducing feel of wood handled hammers over those with solid steel or fiberglass handles. Hickory wood handles are often the preferred choice of professionals because of the natural feel of the wood and a common perception is that fatigue is reduced at the end of the day when using such.
Past attempts to reduce undesirable results from using hammers include designs which incorporate dampers of shock absorbers of various kinds to produce what is referred to as "dead blow" hammers. One of the earliest attempts to produce such a hammer is reflected in U.S. Pat. No. 1,045,145 issued in November 1912 to E. O. Hubbard. Hubbard explains that the head of a "dead blow" hammer struck against a surface will be forced against a cushion, such that the cushion absorbs a portion of the shock impact caused by the strike.
Several early approaches for reducing recoil in hammers are summarized in U.S. Pat. No. 2,604,914 to Kahlen issued in July 1952. In particular, Kahlen indicates that by 1952, known methods for reducing recoil included placing either a slug, a charge of round shot, or a charge of powdered material in a chamber immediately behind a striking face of the hammer, such that an object(s) placed behind the striking head will absorb some of the forces produced by the hammer strike. The particular approach disclosed in Kahlen involved the placement of a charge of irregularly shaped hard heavy particles in a chamber immediately behind the striking head of a hammer. In addition to solutions involving cushions and charge loads, several solutions utilizing resilient members, such as elastic inserts and springs, were proposed to address the hammer strike problems, whereby a portion of the energy developed from the hammer strike is dissipated through the resilient member. Other designs such as that disclosed in U.S. Pat. No. 5,408,902 use a "lagging mass", which is positioned to move towards the striking portion of the hammer head upon impact, thus impacting the striking portion to reduce hammer recoil. Previous shot filled hammers have been limited: (i) because the requirement for a hollow chamber renders the size of such hammers out of proportion to their weight; and (ii) because, unless a special shot mixture is utilized, the shot is often not useful in preventing hammer recoil. Moreover, in prior art "dead blow" hammers, the prying and nail pulling capability of common claw hammers has been forfeited in the attempts to reduce vibration and recoil.
Further discussion of the prior art and its associated shortcomings us provided in U.S. Pat. No. 1,045,145; in U.S. Pat. No. 2,604,914; in U.S. Pat. No. 2,928,444: in U.S. Pat. No. 4,831,901; in U.S. Pat. No. 5,118,117; in U.S. Pat. No. 5,408,902; and German Patent No, 1,273,449.
Thus a need exists for a shock absorbing hammer which includes a claw feature for pulling nails and prying, and which addresses other problems associated with prior art shock absorbing or dead blow hammers.